Only valid for active forum users. Active means at least 30 postings within the last 30 days (no spam postings). This will automatically being checked at www.starbike.com shopping basket so make sure that you are logged in at the WW board!If there does not appear a WW discount position when you check out you do not have enough postings!

Hoping someone might have an answer to this. I am using Dura Ace Di2 on my 2012 Supersix EVO with the Si crank and Canonndale chainrings.When using the 11 or 12 tooth rear with 53 chainring combination the chain skips wildly when any pressure is applied to the pedals and before too long the chain flies off the front chainring on to the crank. I have checked the rear derailleur alignment numerous times and it seems to be perfectly aligned both with the chain on and off. The front derailleur also seems ok.What I do notice is an obvious flex in the 53 chainring regardless of the trimming of the front derailleur, so much so the chain rubs every pedal revolution. I am suspecting the issue is the soft as butter canonndale chainrings causing most of the problems.I am considering a set of Praxis works chainrings as I've read in so many reviews theyre shift performance is excellent and very stiff also.Any advice would be appreciated, thanks all.

My best friend is running Ultegra Di2 with Cannondale SISL cranks, and with the Cannondale rings he was having nothing short of major shifting problems. Finally, he swapped out the chainrings for some FSA, installed a Dura 7901 chain, and since then it's all been resolved. (He had considered the Praxis, but obviously they are much pricier than the FSA.)

Not claiming to know the how's or why's, merely that he made the above changes and all his problems disappeared. In trying to sort out his issues, he spoke to several people who were experiencing similar problems. I thought the stiffness of the Cannondale rings should be fine (some pretty strong professionals use them), but nonetheless, he's much happier now.

Are you using a Conex link? That will do it! I switched to a KCMC link. Check that the high limit screw is set properly on the rear mech. It needs to over shift then come back. Shimano recommends one full turn out after it has hit the stop.

Thanks to everyone for all the suggestions. The Canonndale chainrings are pretty flimsy compared to the Dura Ace ones on my other bike that's for sure. The problem is not in the BB, it's tight and smooth. I'm using a KMC Ti N 10XL chain with KMC link, might get ride of the link and use a pin, never liked em' anyway. Certainly think the rear derailleur could do with over-turning the high limit screw though.